Okay, I've been playing it for most of the weekend and a keyboard easily suffices.
Graphics and gameplay are generally good, though FPS does drop when you enter the car showrooms. Having said that it's still good during races and I'm not that far off the minimum spec processor (I have 3ghz P4, game recommends min 2.8Ghz P4). The overall level of difficulty isn't too easy but it's lower than I had expected and, at least for the lower end races where driving skill isn't measured, there's definitely rubber-banding going on. Take a dive into a tree or four and you can still win.
I haven't tried the multi-player options much but they look good. As well as racing wheel to wheel, you can post challenges for other people to try. At the end of the set period, the person with the best time/score takes all the entrants' fees.
Someone has said that in achieving 100% game completion, 89% can be achieved in single player mode so if you're not into multi-player, there's still enough to do but you won't get the full feeling of the game.
Official release for the US/Asian markets is tomorrow, 20th March. EU got it last friday, AUS/NZ have to wait until 30th March.